Regex::Explain Appears to lack ability to comprehend, or even emit, many
of the new perl regex features.
1. Named Capture groups:
Simply Deleted From Output
2. (?(DEFINE)) structures:
Completely lost
3. (?&ref) references to DEFINE'd strucutres
Can break output horribly
As such, its entirely useless for any complex regex.

Here is just a quick update on this bug.
No steps have yet been taken to support these newer regex features.
No significant updates to the module have been made since Perl
version 5.6 because the original module author (PINYAN) has been too
busy to address this issue.
I (GSULLIVAN) received permission from the original author to become
a co-maintainer of this module. Fixing this bug will not be trivial
for me. It will require me to understand the module code in detail
as well as become familiar with these new regex features. Therefore, I
can not commit to any timeframe for adding these new features.
Patches and tests are welcome.
So that others will be more aware of this issue, I added a LIMITATIONS
section to the POD in version 4.01.
I'd like to note that the following statement by kent.fredric is misleading:
"As such, its entirely useless for any complex regex."
The module can be used to explain all regular expressions, complex or
simple, which do not include the new syntax introduced in Perl 5.10
three years ago (2007). This means that it can handle all regexes
written during the first 20 years of Perl's existence. That's a lot
of regexes!